Railway switch mechanism



Jan. 9, 1968 R W|| HE| M ET AL 3,363,097

RAILWAY swims MECHANISM 3 Sheets-Sheet l Filed May 10, 1965 Wmv. .m oN

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B Paul E.Redelmam Jan. 9, 1968 .1. R. WILHELM ET AL RAILWAY SWITCH MECHANISM 3 Sheets-Sheet 2 Filed May l0, 1965 n .fmg dmnw @mim www WRRW I M m VM.. ou .do PM w ma Jan. 9, 1968 R, wlLHi-:LM ET AL 3,363,097

RAILWAY SWITCH MECHANISM 3 Sheets-Sheet 5 Filed May lO, 1965 5 6 m o 6 4\\\ 4\ 315: M e 3 5 4 M 6 w L w .w .wwfi W .i

am sm a@` melmmm lfume m www. o v .RKMM mwa@ www Pw J Ps2-| Patented Jan. 9, "i968 3,363,097 RAILWAY SWITCH MECHANISM John Roy Wilhelm, Clarendon Hills, and Paul E. Redelman, South Holland, lll., assignors, by mesne assignments, Abex Corporation, a corporation of Delaware Filed May 1G, 1965, Ser. No. 454,489 4 Claims. (Cl. 246-393) This invention relates to a railroad switch stand.

'Ihe present invention is directed to a railroad switch mechanism for throwing switch points from limit positions between stock rails. It sometimes occurs that the switch points are prevented from being completely thrown to `an opposite limit position because of some obstruction. When such obstruction to complete switching occurs, the switch points are, in eiFect, in an open position so that a locomotive passing therethrough is derailed. When the switch machine is .being controlled from a remote tower, the operator may fail to observe the open switch condition; or the operator may be too slow to institute remedial action to prevent a derailment.

Manifestly, such an open switch condition is a safety hazard, and accordingly an object of the present invention is to eliminate an open switch condition caused by the failure of switch points to complete their movement from an original lim-it position to an opposite limit position. More particularly, a further object of the invention is to return automatically the switch points to their original limit position after they have been stopped short of the other limit position by an obstruction or the like. Thus, the locomotive or train moving over the switch points will move down a track rather than through an open switch `and being derailed.

A further object of the invention -is to prevent an open switch condition in a switch machine, which is capable of both manual and power operation. Another object of the invention is to disable power operation of a switch machine while the switch points are being thrown manually thereby preventing the operator from personal injury by a simultaneous manual and power operation of the switch machine.

Another object of the invention is to eliminate the directional valve control by means of a unique fluid operated switch machine capable of alternative operation with a manually operable switch stand.

Other and further objects of the present invention will ybe apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, shows preferred embodiments of the present invention and the principles thereof and what is now considered to be the best mode contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

FIG. 1 is a plan view of a switch machine and its connection to the switch points and constructed in accordance with the preferred embodiment of the invention;

FIG. 2 is an elevational view of the switch machine of FIG. 1;

FIG. 3 is a plan view of the power switch machine with its cover removed to show its internal operating mechanisms;

FIGS. 4A through 4F are partial detailed views illus- -trating operating sequences when actuating the cam during the throw of the switch points.

FIG. 5 is a sectional View showing a switch for disabling the power switch machine;

FIG. 6 is a partial sectional View of a manual switch machine; and

FIG. 7 is a schematic electrical diagram of a control circuit for controlling the power switch machine of FIG. 3.

Referring now to the drawings and more particularly to FIG. 1, there is illustrated part of a railroad switch including two stock rails `20 and 21, which are spiked in the usual fashion to the tie T, and two movable switch points 23 and 24, which are connected together by a conventional throw rod 27. The railroad switch is conditioned for straight through movement for the locomotive when in .the position illustrated in FIG. 1.

The conventional mode of throwing a railroad switch from one of its set or limit positions to the other set or limit positions is by means of a mechanical switch stand 30, FIG. 1, which includes an operating or throw handle 31 for throwing the internal mechanism of the switch stand to operate a connecting rod 32 to operate the throw rod 27 to move the switch points 23 and 24. The switch stand 30 is spiked to a pair of ties T in the conventional manner and is shown positioned outwardly of a power switch machine 35.

The railroad'switch in the present instance is arranged for dual operation either by the lmanual switch stand 30 or by the power switch machine 35, each of which is adapted to reciprocate a connecting rod 3S attached by an adjustable bracket means 39 to the throw rod 27 for the switch points 23 and 24. The manual switch stand 30 may 4thus be thrown by an operator who turns the handle 31 through approximately 180 from a position overlying the top surface of one tie T to a position generally overlying the top surface of the opposite tie T,.

in the conventional manner. On the other hand, the power switch machine 35 may be remotely operated by incoming signals that are part Aof an electrical control circuit from a remote operating station such as a control tower (not shown).

Heretofore, it has been possible that an operator will begin to throw the switch lby turning movement of the handle 31 of manual switch stand 30 at a time when the tower operator may institute power actuation of the power switch machine 35. The attempt of simultaneous operation of the switch by the manual switch stand 30 and the power switch machine 35 results in unexpected forces which may cause personal injury to the operator, except for the disabling of the power switch machine 35, as practiced in accordance with the present invention.

The preferred form of the manual switch stand is best understood from FIG. 5, which is generally similar to FIG. 6 of U.S. Patent No. 3,136,509, wherein the preferred form of the manual switch stand is described in detail. The disclosure of the manual switch stand disclosed in U.S. Patent No. 3,136,509, is hereby incorporated by reference as if fully reproduced herein.

Brielly, the throw handle 31 of the manual switch stand 30 is connected to a hub portion 40, FIG. 5, of a spring base element 41 which is journaled for rotation within a loosely fitted bearing portion 45 on a two-piece housing sleeve 43.

For the purpose of detection of the beginning of the manual operation of the manual switch stand 30 by turning movement of the throw handle 31, a limit switch 50, which is mounted on the base B of the manual switch stand 30 detects turning movement of the hub portion 40 with the throw handle 31. More particularly, the hub portion 40 is provided with a pair of cutouts 46 and 47 spaced apart on the exterior surface of the hub 40.

The limit switch 50, FIGS. 5 and 6, is secured to the base casting B by a suitable lbracket 52 and has a sensing element or plunger 54 with a cam follower or roller 55 on the terminal and outward end of the plunger 54 for cam following engagement with the outer peripheral surface of the hub 40. As the hub 40 begins to rotate with the turning of the throw handle 31, the plunger 54 is camrned inwardly into the limit switch 50 to operate contacts which disable the power operation of the power switch machine 35, as will be explained hereinafter in greater detail.

The limit switch 50 is held in its inward disabling position throughout the greater portion of the 180 rotation of the hufb 40 with the throw handle 31, until the `opposite cutout 46 of the hub 40 is reached at which time the plunger 54 under biasing force again moves outwardly to bring the cam following roller 55 into the cut-out 46. Thus, the contacts in the limit switch 50 are again operated to permit completion of a control circuit or operation of the powerV switch machine 35 by an operator at a remote location.

The illustrated location of the detection limit switch 50 and its cooperation with the hub 40 is only one of a number of other locations which could be employed to detect movement of the manual switch handle 31 by an operator. For instance, a pair of limit switches may be provided to engage the arm portion 55 of the throw arm 31 in each of its opposite limit positions; therefore, when the throw arm 31 is moved from each of its respective limit positions, a limit switch is actuated.

Moreover, a sensing means like the switch 50 may be located to detect movement of the crank arm or other movable portions of the switch stand 30 from its at-rest position and still fall within the purview of the present invention. During the rotation of the throw arm 31, such other movable portions such as a toggle link mechanism 60, move through approximately 180 of movement as does the vertical spindle 61. Either of these could be sensed by a sensing means such as a switch 50. The rotation of the throw arm 31 causes the spring base 41 to turn and move the toggle link 60 which turns the vertical spindle 61.

As explained in greater detail in U.S. Patent No. 3,136,509, the spring 64 is a strong spring which is compressed during initial rotation of the spindle 61.by the power switch machine and which thereafter expands to complete rotation of the vertical spindle 61 and thereby movement of the switch points 23 and 24 to bring the points into rm Vengagement with one of the stock rails 20 and 21. That is, the power switch stand 35 is so constructed that the centered or half way turning of spindle rotation is an unstable position so that the spring 64 acts as an overcentering spring to assure that the switch points and the vertical spindle 61 are not left on a dead center position which would constitute an open switch position for the switch points 23 and 24.

Rotation of the vertical spindle 61 by operation of the throw handle 31 causes rotation of the spindle 61 and its lower hub 65 connected by an eye bolt 66 in turn connected to the first connecting .rod 32. The lower end of the spindle 61 functions as a crank to reciprocate the connecting rod 32 which is in turn connected to the connecting rod 38, FIG. 1, for reciprocation of the throw rod 27 to move the switch points 23 and 24 between their home or limit positions.

As best seen in FIG. 2, the connecting rods 32 and 38 are joined by a bracket 70 which in turn is connected by an eye bolt 72. The latter is connected to a crankboss 73, FIG. 2. The crankboss 73 is formed on the bottom of a spindle cam 74 within the power switch machine 35.

The spindle cam 74, FIG. 3, is journaled for rotation about a vertical axis 75 in a hub 76- of a base casting 77, FIG. 1, for the power switch machine 35. As will be explained in greater detail hereinafter, the spindle cam 74 is adapted to be turned in clockwise and counterclockwise directions by a fluid operating means 80 which includes a double acting hydraulic cylinder 81 with an extendible piston rod 82 having a cam ball 83 secured on the outer end thereof.

The turning of the spindle cam 74 and thereby its crank portion 73 reciprocates the connecting rod 38 and causes a switching operation, which can best be understood from a consideration of FIGS. 4a-4f. The leftmost position shown in FIG. 4 corresponds to the at-rest position for the spindle cam 74 with the switch points 23 and 24 in the limit position shown in FIG. l. Operation of the hydraulic cylinder 81 to move the piston rod 82 outwardly of the cylinder 81 causes the cam ball 83 to slide downwardly into a cam pocket 84, FIG. 4b, and to pivot the cylinder 8-1 about its pin connection 88 to the base 77.

Further outward movement of the piston rod 8,2, as seen in FIG. 4c, causes pivoting of the spindle cam 74 in the counterclockwise direction to bring the cam and cylinder into its half-thrown position, or slightly therepast, at which time the crank portion 73 of the spindle cam 74 has pulled the connecting rod 32 suiciently to turn the vertical spindle 61 in the manual switch stand 30 to compress the spring 64 and to move past its center position, whereupon the overcentering spring 64 becomes operative to complete the counterclockwise rotation of the spindle cam 74. Upon completion of the counterclockwise rotation of the spindle cam 74 by the spring 64, the switch points 23 and 24 are moved rightwardly, as viewed in FIG. 1, to bring the switch point 24 into rm engagement with the stock rail 21 whereby the approaching locomotive is turned out, that is, switched onto a side track.V

The complete extension of the piston rod 82 is followed by an automatic withdrawal of the piston rod 82 by reversing the ow of hydraulic -uid within the double acting hydraulic cylinder 81. During return of the piston .rod 82, the spindle cam 74 remains in its turn out limit position and the switch points 23 and 24 remain thrown to this turn out limit position. When the cam ball 83 moves past the apex 85 of the spindle cam 74, as seen in FIG. 4e and 4f, the cylinder 81 pivots to its generally centered position, as seen in FIG. 4f.

More particularly, the cylinder 81 is centered by means of a pair of right and left centering arms 89 and 91, FIG. 3, which are interconnected by a tension spring 90. The arms 89 and 91 are respectively pivoted at 92 and 93 to the base casting 77.

To rotate the spindle cam 74 in the clockwise direction from the position of FIG. 4, it is necessary to institute a second cycle of operation of the hydraulic cylinder 81 to force the ball cam 83 into an opposite cam pocket 95 on the cam 74. Such further extension of the piston rod 82 rotates the spindle cam 74 in a clockwise position to at least a Vhalf-thrown position whereupon biasing spring 640i the manual switch stand 30 is again operative to complete the throw to the switch points 23 and 24 and movement of the spindle cam 74 to its full clockwise or limit position, as shown in FIG. 4a.

For the purpose of operating the hydraulic cylinder 81, there is disposed beneath the housing cover 98 for the power switch machine 35 and an electric, reversible Vmotor 99, which is suitably connected to power inletcables 100. The reversible motor 99 is directly connected to a hydraulic pump 102, which in turn is connected to exible hydraulic hoses 103 and 104, leading to opposite ends of the hydraulic cylinder 81.

When the piston rod 82 is being driven outwardly of the cylinder 81, fluid is pumped from the pump 102l through the hydraulic hose 103 to the rearward end of the hydraulic cylinder 81 to force the piston rod 82 outwardly. Conversely, when retracting the piston rod 82,

the motor 99 is reversed in its direction of rotation, as

is the pump 102. Thus, fluid is pumped under high pressure through the hydraulic hose 104 to the forward end of the cylinder 81 to drive the piston rod 82 inwardly into the hydraulic cylinder 81.

The preferred manner of detecting when the piston rod 82 has moved to its external and extended position is by means of a first pressure switch PS1, FIG. 3, which is connected by a line 110 to the hydraulic line 103 so as to detect the build up of pressure of the hydraulic fluid when the piston has moved to its maximum extended movement within the hydraulic cylinder 81. In the preferred embodiment of the invention, the usual operating pressure is approximately 500 pounds p.s.i. and the pressure switch PS1 is actuated when the iiuid pressure builds up to approximately 1,000 pounds p.s.i., which event occurs after the piston rod 82 is fully extended. The pressure switch PS1 controls a pair of contacts in the control circuit for the reversible motor 99 to cause reversal of the rotation of the motor M and thereby the return of the piston rod 82.

In a similar manner, a pressure switch PS2, FIG. 3, disposed adjacent the pressure switch PS1 is connected by a line 112 to the hydraulic line 104 to the forward end of the hydraulic cylinder 81 to detect the build up of the fluid pressure to approximately 1,000 pounds p.s.i. indicating that the piston and piston rod 32 have been driven in the return direction to their full retraction. The pressure switch PS2 is adapted to shut o the reversible motor 99 in a manner to be explained hereinafter in conjunction with the control circuit shown in FIG. 7.

An important aspect of the present invention is the detection of the movement of the switch points 23 and 24 to their limit positions so that there is assurance that the switch is fully thrown. An open switch condition may result in the locomotive or train running onto the ground and thereby it is to be avoided as a safety hazard. It is preferred to protect the sensing means for ydetecting the movement of the switch points to their full extent, from adverse environmental conditions such as snow and ice.

Thus, the sensing means which includes limit switches LS3 and LS4, FIG. 3, are disposed beneath the cover 98 within the power switch machine 35. The limit switch LS3 is adapted to be operated by a nose .120 on the spindle cam 74 when the spindle cam 74 is in its furthermost clockwise position, that is, limit position, which corresponds to the switch points 23 `and 24 being in their straight through limit position illustrated in FIG. 1. Conversely, counterclockwise rotation of the spindle cam 74 moves the nose 120 in a counterclockwise direction to aculate a lever arm 122 for the limit switch LS4 to actuate limit switch L84 when the switch points 23 and 24 are in their opposite, turn out, limit positions.

`"/hen the spindle cam 74 is moving between its opposite limit positions or when it is obstructed from moving to its fullest extent, the limit switches LS3 and L84 detect such a condition and cause automatic reversal of the switch points to their original limit position, which may be either the straight through or turn out limit position, as will be explained hereinafter in greater detail.

The limit switches L83 and L84 are connected by cables 125 and 126, FIGS. 1 and 3, to an electrical control box assembly 130. The electrical control box assembly 130 is also connected by appropriate cables 131 and 132 to the pressure switches PS1 and PS2. The internal components of the electrical assembly 130 are best explained hereinafter in conjunction with FIG. 7.

The control circuit 13S illustrated in schematic form in FIG. 7, controls operation of the power switch machine 35 either by operation of a push button switch 136 located at a remote control station RS or a push button switch 137 located on the outside of the control box 130, FIG. 1. The usual manner of operation of the power switch machine 35 is by the operator in a control tower, which constitutes the remote station RS, having the push button switch 136.

For purposes of installation and servicing, it is preferred to have a local push button switch 137 and an on-of switch SS secured adjacent to one another on the switch box 130 within the housing cover 98. Local operation of the switch is by means of the manual switch machine 30 except during times of repair or servicing when the cover 98 is removed. Suitable power and signal wire are brought in by cables 106 to the control box 130; and upon closure of the remote switch button 136, a circuit is completed for driving the reversible motor M through either its forward driving coils 99F or its reversible coils 99K, FIG. 7. Closure of the switch 136 will complete the circuit for the forward coil 99E over the following path: from lead 100; switch SS; disconnect contacts DS; lead now closed, push button 136; lead 141; now closed, pressure switch contacts PS1-1; motor coil 99F; normally closed, overload contacts 144, to the opposite power lead 100.

Thus, the motor coil 99F is energized to start rotation of the motor 99 to drive the pump 102 to pump uid through the hose 103 to drive the piston rod 82 outwardly of the cylinder 81. The motor starting circuits of coils 99F and 99R (not shown) each have holding contacts F-l and R-l to hold circuits for motor coils F and R when the push button 136 is released. Consequently, with release of the push button 136, the hydraulic cylinder 81 continues to extend its pistou rod 82 to drive cam 74 through the leftmost, sequential operations in FIGS. 4a, 4b and 4c.

When the piston rod S2 is fully extended as in FIG. 4c, the pressure begins to build up with continued rotation of the pump 102 until the pressure switch PS1 is operated to open its contacts PS1-1 breaking the previously described circuit through the motor coil 991:. As the pressure switch PS1 opens its pressure contacts PS1-1, it closes its contacts PS1-2, FIG. 7, to complete a circuit for the reverse coil 99K of the motor 99 through a circuit including: lead 100; selector switch SS; lead 148; now closed, pressure contacts PS1-2; now closed, contacts PS2-1, coil 99K and normally closed overload contacts 144 to the opposite power lead 100.

Energization of the reverse coils 99R of the motor 99 causes the motor M and the pump 102 to reverse their directions of rotation. The higher pressure of fluid from the pump 102 is forced through the hose 104 and into the forward portion of the cylinder 81 to drive the piston and piston rod 82 toward the rear of the cylinder, as shown in FIGS. 4d and 4e. When the piston and piston rod 82 are fully retracted, the operating pressure begins to build up within the hose 104 and pump 102 from about 500 pounds p.s.i. to about 1,000 pounds p.s.i. This increased pressure actuates the pressure switch PS2 to open its c011- tacts PS2-1, FIG. 7, thereby breaking the immediately above traced circuit for operating the reverse motor coil 99K. Thus, the motor 99 is de-energized.

The limit switches LS3 and LS4, which are operated by the spindle cam 74 also were activated during the movement of the switch points from the position of FIG. 1. According to FIG. 7, signal lights 150, FIG. 7, are provided to indicate the switch condition. Such signal lights may at the switch location only, however, have additional signal lights that are usually provided in the control tower to indicate the condition of the switch to the remotely located operator. The upper signal light ST indicates that the switch points are in the straight through condition of FIG. 1. The light 150 ST is usually a green light. A middle light 150 R is a red light, which indicates that the switch points are open, and the turn out light is an amber light 150 T which indicates that the switch points are switched to cause a turning movement of a railroad locomotive moving through the switch.

The signal lights 150 are controlled by the position of the switches LS3 and LS4, as will be hereinafter explained. With the switch points 23 and 24 in the position illustrated in FIG. 1, the straight through green light 150 ST is lighted over a circuit from: lead 100; now closed, upper contacts LS4-1 and LS3-1 of the limit switches LS4 and LS3, lamp coil of the green light 150 ST to the opposite power lead 100. Immediately upon movement of the spindle cam 74, as illustrated in FIG. 4b, the

limit switch LS3 is operated and moves from its upper contact to break the circuit for the green, straight through light 150 ST; and the limit switch LS3 closes its contacts LS3-2 to complete a path: through lead 155 tothe red (open) light 150 R.

If the switch points are unobstructed in their movemerit to their opposite limit position, the turn out position, the spindle cam 74 rotates to its fullest extent to operate the limit switch LS4. Operation of limit switch LS4 by arrival of the switch points 23 and 24, in the turn out position extinguishes red light 150 R by opening contacts LS4-1. Closingof contacts LS4-2 completes the circuit path for the lamp 150 T from lead 10i); through now closed contact LS4-2; lead 157 and lamp coil of the light 150 T to the opposite power lead 100.

On the other hand, if the switch points were not completely closed, that is in the limit position, the spindle cam 74 would not have operated the limit switch LS4 to complete its lower contacts and the lamp 150 R would have remained red and a circuit would have been completed to a control relay CR, FIG. 7, to cause reverse movement of the switch points back to their original straight through position of FIG. 1.

The limit switches LS3 and LS4 could be located at the respective stock rails 23 and 24 and would function in the same manner to indicate the movement of the switch points to their limit positions. Alternatively the limit switches could be situated to detect the full reciprocation of the connecting rods 32 or 38.

For purposes of description, let it be assumed that the switch points have started their movement from the straight through position; and have become obstructed while the switch points are in their open position. That is the switch points 23 and 24 are being held against complete movement to the turn out position. pair of contacts AUX-R, FIG. 7, in the starter circuit for the motor are closed with each energization of the reverse coil 99R. D

With the switch points obstructed, the continued operation of the pump 152 builds up suflicient pressure to open the contacts PS1-2 to complete the circuit for the 4reverse motor coil 99R to retract the piston rod 82. With the piston rod S2 retracted, pressure builds up and actuates switch PS2 to open its contacts PS2-1. This completes a lirst cycle of operation of the motor M.

During the retraction of the piston rod 82 and reverse rotation of the motor 99, the auxiliary contacts AUX-R are closed and complete a path for operating the control relay CR to initiate a second cycle of operation of the motor M and the hydraulic cylinder 81 to cause the switch points to return to their straight throng positions. The circuit for the control relay CR remains completed because of the open switch condition; this circuit for the control relay CR extends from: lead 100; now closed, contacts LS4-1; lead 158; now closed, contacts LS3-2; lead 155; lead 159; now closed contacts AUX-R; coil of relay CR to opposite power lead 100. As the control relay CR is operated, it closed its normally open holding contacts CR-l to hold relay CR energized as the contacts PS2-1 were opened to break the circuit for the reverse motor coil 99R.

The control circuit means including control relay CR at this time, causes an automatic reversal of the switch points to their straight through position by completing a circuit for the forward motor coil 99F through its normally opened, relay contacts CR-Z; this circuit being through power lead 100; selector switch SS; lead 14S; now closed contacts CR-2; now closed pressure switch contacts PS1-1; coil 99F and overload contacts 144 to power lead 100. Thus, the piston rod 82 moves outwardly into the cam pocket 95 to afford a clockwise rotation for the spindle cam 74 to return the switch points to their straight through position.

As the piston rod 82 moves to its fully extended position and the pressure builds up, the pressure switch contacts PSL-1 are opened to break the forward motor coil circuit and to establish the reverse motor coil circuit in the hereinbefore traced circuit. The return of the switch points to their straight through position causes the cam nose on the spindle cam 74 to operate the limit switch LS3 to move its swinger into engagement with the upper contact LS3-1 thereby breaking the cir-A cuit for the control relay CR through the limit switch contacts LS3-2. De-energization of the control relay CR opens its holding contact CR-l and its contacts CR-Zk thereby preventing another operation of the forward motor coil circuit as hereinbefore stated. Thus, a locomotive or railroad cars will not be derailed by an open switch condition; the locomotive being switched straight through rather than moving in the turn out direction as originally desired.

The control relay CR will function generally in the same manner to return the switch points 23 and 24 to the turn out position if the switch points are obstructed from moving to the straight throng position. With the switch points 23 and 24 in the turn out position, the positions of the limit switch contacts L83 and LS4 are reversed from that shown in FIG. 7. That is, the swingers of the respective limit switches LS3 and LS4 are engaging their lower contacts, LS3-2 and LS4-2.

Upon closure of the switch 136, the forward motor coil 99F is energized and the spindle cam 74 rotates in a clockwise direction. Also, the limit switch contacts LS4- 2 are closed to complete a circuit over lead 158; now closed, lower contacts LS3-2 of limit switch L53 and lead to the red light 150R. If the switch points fail to reach the straight through limit switch position and hence fail to reverse the positiiton of limit switch L53 from contact LS32 to LS3-1, the control relay CR is energized over a path from lead now closed contacts LS4-1; lead 15S, now closed, contact LS3-2; lead 155; auxiliary return contacts AUX-R; and coil of relay CR to the opposite Vlead it?.

`Operation of the control relay CR closes its holding contacts CR-l and its contact CR-2 to complete another energization cycle of the motor 99 through its forward coils 99F and 99R to cause reciprocation of the piston rod S2 to `return the spindle cam 74 to its counterclockwise position. Return ofthe spindle cam 74 to its counterclockwise position, moves cam nose 120 to actuate limit switch LS4 to open contact LS3-1 thereby breaking the circuit for the control relay CR. Relay CR opens its contacts CR-2 and breaks the motor cycle with the switch points returned to their turn out position and the motor 99 de-energized.

The control circuit means, as exemplified in FIG. 7, also contains the manual, disconnect switch contacts DS for disabling operation of the power switch machine 35 from operation by closure of the push button switch 135 at the remote station RS. yIt will be remembered that disconnect contacts DS of thelimit switch 50 remain open through approximately rotation of the throw Y handle 31. With the handle 31 in either one of its eX- treme throw positions, the limit switch plunger 54 is eX- tended and the limit switch contacts DS are closed to permit completion of the operating circuits for either the motor coils 99F and 99R by closure of the remote switch 136.

From the foregoing, it will be seen that the present invention aiords a unique inter-relationship of a manual switch machine and a power switch machine so as to disconnect the operation of the power switch machine upon beginning to throw the switch points by the manual switch stand.

It will also be recognized that the present invention alfords a novel manner of controlling the return of the switch points to their initial position when the switch points are obstructed or prevented from moving to the opposite limit position thereby preventing the occurrence of an open switch position which might be the cause of a train derailment.

Hence, while preferred embodiments of the invention have been described and illustrated, it is to be understood that they are capable of variation and modication, and we therefore do not wish to be limited to the precise details set forth, but desire to avail ourselves of such changes and alterations as fall within the purview of the following claims.

We claim:

1. In a power operated switch machine for throwing switch points between initial and second limit positions and operable, upon failure of the switch points to cornplete a throw to the second limit position, to return the switch points to their initial limit position; a reversible electric motor, a hydraulic pump driven by said motor, a hydraulic piston adapted to be driven in opposite extending and retracting directions by hydraulic lluid from said pump, rotary cam means engageable by said piston and adapted to be turned in opposite directions by successive extension strokes of said piston, connecting means operatively connecting said cam means with the switch points to move the switch points between either limit position upon a predetermined amount of turning movement of said cam means in one direction or the other; electrical circuitry for said motor including a starting circuit, detecting means in said circuitry to detect arrival of the switch points at the second limit position during an intended throw of the switch points and effective thereupon to reverse the motor to cause retraction of the piston thereby conditioning the piston for the next extension stroke thereof which will reverse the switch points from the second to the initial limit position; said detecting means also being efective to reverse the motor to cause retraction of the piston in the event the switch points en- 3 counter an obstruction and fail to reach the second limit position during an attempted throw of the switch; and recycling means in the circuitry for said motor to cause a second cycle of the motor when the obstructing event is encountered, to thereby produce re-extension of the piston and return of the switch points to the initial limit position when there is failure to reach the second limit position because of an obstruction.

2. A switch machine according to claim 1 including manually operable means for throwing said switch points between said limit positions, and sensing means in the circuitry for said motor to disable the motor circuit thereby safeguarding the operator during manual operation of the Switch.

3. A switch machine according to claim 2 wherein said manually operable means includes a throw handle and said sensing means is a limit switch.

4. A switch machine according to claim 3 wherein the manually operable means includes a linkage means and a Spring means urging said switch points to a limit position, operation of said switch points through said motor compressing and releasing said spring means to urge said linkage means to assist in throwing said switch points.

References Cited UNITED STATES PATENTS 1,886,987 l1/l932 Taylor 246-393 X 2,045,930 6/1936 Taylor 246-393 2,092,828 9/1937 Bone 246-393 X 2,829,851 4/1958 George et al. 246-219 X 2,852,667 9/1958 Haines 246-219 X 3,127,138 3/l964 Wilson et al. 246-393 3,158,345 11/1964 Wilhelm et al. 246-258 ARTHUR L. LA POINT, Primary Examiner.

S. B. GREEN, R. A. BERTSCH, Assistant Examiners. 

1. IN A POWER OPERATED SWITCH MACHINE FOR THROWING SWITCH POINTS BETWEEN INITIAL AND SECOND LIMIT POSITIONS AND OPERABLE, UPON FAILURE OF THE SWITCH POINTS TO COMPLETE A THROW TO THE SECOND LIMIT POSITION, TO RETURN THE SWITCH POINTS TO THEIR INITIAL LIMIT POSITION; A REVERSIBLE ELECTRIC MOTOR, A HYDRAULIC PUMP DRIVEN IN OPPOSITE EXTENDHYDRAULIC PISTON ADAPTED TO BE DRIVEN IN OPPOSITE EXTENDING AND RETRACTING DIRECTIONS BY HYDRAULIC FLUID FROM SAID PUMP, ROTARY CAM MEANS ENGAGEABLE BY SAID PISTON AND ADAPTED TO BE TURNED IN OPPOSITE DIRECTIONS BY SUCCESSIVE EXTENSION STROKES OF SAID PISTON, CONNECTING MEANS OPERATIVELY CONNECTING SAID CAM MEANS WITH THE SWITCH POINTS TO MOVE THE SWITCH POINTS BETWEEN EITHER LIMIT POSITION UPON A PREDETERMINED AMOUNT OF TURNING MOVEMENT OF SAID CAM MEANS IN ONE DIRECTION OR THE OTHER; ELECTRICAL CIRCUITRY FOR SAID MOTOR INCLUDING A STARTING CIRCUIT, DETECTING MEANS IN SAID CIRCUITRY TO DETECT ARRIVAL OF THE SWITCH POINTS AT THE SECOND LIMIT POSITION DURING AN INTENDED THROW OF THE SWITCH POINTS AND EFFECTIVE THEREUPON TO REVERSE THE MOTOR TO CAUSE RETRACTION OF THE PISTON THEREBY CONDITIONING THE PISTON FOR THE NEXT EXTENSION 